Multi character selective display device

ABSTRACT

A device for selectively displaying one of a plurality of characters at a viewing axis and which is particularly useful for selectively displaying decimal digits representative of numerical values in response to digital electrical signals. The device includes ten pivotal arms spaced in a circle and normally biased outwardly and maintained parallel to a central viewing axis. The free ends of the arms have transparent indicia embedded therein. The arms are selectively pivotable to move their free ends onto the viewing axis to present the indicia for display. The central axis includes means for projecting collimated light through the transparent indicia on the free ends of the levers to project images of the indicia upon a viewing screen. Movement of the selected lever is achieved by novel means which selectively magnetize a core surrounding the central axis and the selected one of the arms to magnetically attract its indicia bearing end onto the viewing axis.

United States Patent 1191 Novak MULTI-CHARACTER SELECTIVE DISPLAY DEVICE [76] Inventor: Warren D. Novak,325 Douglas Road, Chappaqua, NY. 10514 [22] Filed: Dec. 16, 1971 [-21] Appl. No.: 208,640

[52] US. Cl 340/378 B, 340/324 R [451 July 17, 1973 Primary Examiner-John W. Caldwell Assistant Examiner-Marshall M. Curtis Attorney-James. S. Hight, John D. Poffenbcrger etal.

57 ABSTRACT A device for selectively displaying one of a plurality of characters at a viewing axis and which is particularly useful for selectively displaying decimal digits representative of numerical values in response to digital electrical signals. The device includes ten pivotal arms spaced in a circle and normally biased outwardly and maintained parallel to a central viewing axis. The free ends of the arms have transparent indicia embedded therein. The arms are selectively pivotable to move their free ends onto the viewing axis to present the indicia for display. The central axis includes means for projecting collimated light through the transparent indicia on the free ends of the levers to project images of the indicia upon a viewing screen. Movement of the selected lever is achieved by novel means which selectively magnetize a core surrounding the central axis and the selected one of the arms to magnetically attract its indicia bearing end onto the viewing axis.

17 Claims, 5 Drawing Figures PA'IEmEu-Jmv 314L091 SHEH E [If E INVENTOR. I

MULTI-CHARACTER SELECTIVE DISPLAY DEVICE The present invention relates to multi-character display devices, and more particularly to devices for selectively displaying indicia at a common viewing axis. Devices according to the present invention are particularly suitable for displaying numerical decimal digits in response to digital electrical signals.

There are a wide range of applications wherein it is desirable that information of various forms be visually displayed. In one wide class of applications, it is desirable to display the information in the form of discrete indicia, symbols, or characters. Display devices according to the present invention are generally suitable to applications of this class. Such applications include, among their most common forms, the display of data from calculators, computers, general communication systems, the outputs of meters and instruments and many other types of devices. The application might call for the display of a single character or of several symbols simultaneously.

Most frequently, the information is desired to be displayed in the form of indicia representative of the character equivalents of certain digital data. The most common desired form of such display is the display of decimal numerical digits representative of the digital numerical values of certain electrical signals.

Accordingly, the present invention is described in connection with the one specific embodiment thereof wherein decimal digit numerical data is desired to be displayed, as for for example, when used in connection with computers, calculators, and digital output meters and instruments. The device described is effective to display a single selected character, but devices of this type may be used in groups to form a register to display several selected characters simultaneously.

One important feature which display devices of this type must have is the ability to display clear images of the characters or indicia, since the visual perception of the information which they display is their primary objective. In this respect, the characters displayed should be easily recognizable and easily distinguishable from one another. Furthermore, the size of the characters displayed should be as large as possible, particularly in relation to the size of the display device. In this manner, large images can be presented on limited panel space, and devices can be grouped closely to form registers which present compact groups of large characters for easy visual perception.

It is also important that these display devices be capable of selecting characters in a reliable and repeatable manner and that the devices possess the ability to change from character to character at a high rate of speed. In this respect, the devices can accomodate high speed instruments and can display rapidly changing data from short lived electrical signals without undue lag between data generation and display.

Typically, display devices for these purposes fall into two design classes. The first class includes devices wherein mechanically moving parts are employed in the selection of the character to be displayed. The second class includes devices which have no mechanically moving parts, but instead the selection of the characters to be displayed is achieved by electrical means which selectively generate visual images.

The entirely electronic devices possess generally capabilities of operating at much greater speeds than do the devices with moving parts, which is due primarily to the absence of the mechanical inertia inherent in moving mechanical parts. The electrical devices, however, are usually more expensive and have a higher failure rate, and also possess other disadvantages. One of these other disadvantages is in the difficulty in electronically generating a wide range of clearly recognizable and easily distinguishable images. To do so electrically usually requires a complex optical or electrical system which is frequently bulky and often quite costly.

-On the other hand, mechanicaldevices possess the ability to display a greater variety and type of character, encompassing any geometric shape which can be pictorially represented. Furthermore, mechanical devices are usually more reliable and fail with far less fre quency than do electronic devices. But mechanical devices do possess the inherent slowness due to the difficulty in overcoming the inertia of moving parts, and mechanical devices usually will occupy more space than do their electronic counterparts and thus are less adaptable to the formation of compact display registers and less compatible with the efficient panel and instrument design. Furthermore, the characters of many mechanical devices are not randomly selectable, that is to say, all characters cannot be selected with equal speed. For example, with many devices it is necessary to step through the digits in a predetermined order.

Accordingly, it is a principle object of the present invention to provide a display device which overcomes the disadvantages of the various prior art display devices. The present invention does so by utilizing a mechanical movable selection mechanism to realize the great geometric flexibility in character selection at very low cost, and to also realize the high reliability which mechanical devices provide also at relatively low cost.

Specific objectives of the present invention are to provide, in such a mechanical selection display device, a highly compact mechanism which will operate quickly and respond rapidly to rapidly and randomly changing data.

Accordingly, the present invention is predicated in part upon the concept of providing, in a multicharacter display device, a plurality of pivotal levers each having a character-bearing free end selectively positionable between an outer radial position, wherein the character is not visible when viewed along a central viewing axis, and an inner radial position, wherein the character is registered with the viewing axis.

One aspect of the present invention is predicated upon the concept of providing a device of the foregoing type in which the levers are electromagnetically pivoted by polarizing the free ends thereof such that they are attracted toward the viewing axis.

Another aspect of the present invention is predicated upon the concept of providing an electromagnetic lever pivoting arrangement which includes a central winding wound on a core located at the viewing axis and a plurality of oppositely wound lever windings, the lever windings being series connectable with the central winding through a circuit path plated on the levers and central core.

More particularly, the specific embodiment of the present invention includes a group of normally parallel steel levers symmetrically positioned around, and parallel to, a steel tube which houses a light source and suitable collimating lens and defines a viewing axis. The levers at their lower ends are pivotally mounted in notches provided in the periphery of a steel support disc disposed normal to the viewing axis and levers. The levers at their upper ends have radially inwardly extending ears bearing characters which are adapted to be selectively positioned to intersect the collimated light beam directed along the viewing axis when the levers are pivoted to their inner position by unique electromagnetic leverpivoting means. The levers normally occupy outer positions to which they are biased by suitable springs.

The electromagnetic lever pivoting means includes a plurality of independent insulated wire windings respectively wound around different ones of the levers, and a central insulated wire winding wound around the steel tube defining the viewing axis. The upper end of the central winding is electrically connected to the upper end of each of the character windings by means of gold film plated on the pivotal levers, the support disc and the central tube. The lower end of the central winding is adapted to be selectively series connected through a power source with different ones of the character windings by suitable switch means.

Connection of the windings in this manner provides a flow of current therethrough which, by reason of the windings being oppositely wound, polarizes the upper free end of the selected character lever oppositely to the upper end of the central tube disposed along the viewing axis. With the upper end of the selected character lever and central tube oppositely polarized, the selected lever pivots, causing the radially inwardly extending end of the selected character lever to intersect the viewing axis and the source of light to project an image onto a suitable located viewing screen.

In another embodiment of the device, the collimating lens and viewing screen is eliminated, and for example, an opaque plate having a window located at the viewing axis is provided. In accordance with such a modification, the selected character is visible when pivoted radially inwardly to register its free end with the window formed in the plate.

The advantages of the present invention are particularly in the provision of an exceedingly compact display unit of high reliability and having an extremely quick responding electromechanical actuating means. For example, devices according to the present invention have been found to be constructed in cylindrical form with diameters of less than 0.7 inches which have the ability to display numerical characters which are greater than 0.4 inches in height. Smaller devices have been found to be constructable which have an overall diameter of 0.4 inches and have been effective to display characters of 0.25 inches in height. Devices of these dimensions have been found to be operable to reliably display information which changes at the rates of greater than to characters per second, respectively.

These and other objects and advantages of the present invention will be more readily apparent from the following detailed description of the drawings, illustrating one preferred form of a multi-character selective display device according to principles of the present invention, in which:

FIG. 1 is a perspective view of a display register embodying digital display devices according to one preferred form of the present invention;

FIG. 2 is a side view of one of the display devices of the display register of FIG. 1 partially broken away and partially in cross section to illustrate the selective character positioning mechanism of the device;

FIG. 3 is a cross sectional view taken along the line 3-3 of FIG. 2;

FIG. 4 is a cross sectional view taken along the line 44 of FIG. 2; and

FIG. 5 is a schematic diagram of the circuit of the device of FIG. 2.

Referring to FIG. 1, a display register is illustrated which employs a plurality of multi-digit display devices each embodying principles of the present invention. This display register 10 as illustrated includes three digital display devices or modules 11. The register 10 is effective to display digital data from a data unit 12 which supplies the data in the form of electrical signals to a switching and selector device 14 which drives each of the modules 11. These modules each operate to selectively display a single character, which is one of a bank of multiple characters, for visual perception. In the specific embodiment disclosed in these drawings, these devices are each effective to display an illuminated image upon a screen of a selected decimal digit. Each device is effective to display any one of ten decimal digits, zero through nine. Such a device in this embodiment is particularly useful in connection with computers and calculators or in meters and other devices in which numerical data is to be displayed in digital form in response to electrical signals.

The structure of this device can best be understood by reference to FIG. 2, which illustrates in axial cross section one of the modules of this embodiment of the invention.

In its preferred form, the display device 11 includes an elongated housing 21 which is cylindrical in shape. The housing 21 defines a central axis 22. This axis 22 coincides with what will be hereinafter referred to as the viewing axis of the device. The device 11 includes a plurality of arms 23 of a ferromagnetic material such as steel, each arm 23 having a free end 24 which is angulated at approximately with respect to the rest of the arm. The arms 23 are ten in number, and are arranged in normal orientations parallel to the axis 22 and positioned such that each is spaced a fixed radial distance from the cnetral viewing axis 22 at evenly spaced intervals around the periphery of a circle which circumscribes the axis 22. A plate 26 preferably of steel or similar ferromagnetic material is provided within the housing 21 and is mounted in a radial plane with respect to the axis 22 of the device. The plate 26 is rigidly secured to, and electrically insulated from, the housing 21 through any suitable means, which, in the embodiment shown, includes a set of mounting supports 27 rigidly connected between the plate 26 and a mounting plate 28 of insulating material, for example phenolic plastic, which is in turn secured to the housing 21. Positioned in the plate 28 and fixed thereto by press fit are a set of ten symmetrically spaced electrically conductive lugs 29, of for example brass.

Each of the arms 23 is pivotally mounted to the plate 26 at the lower end of the arms 23. The plate 26 is provided for this purpose with a set of ten notches 31 spaced at equal intervals about the periphery thereof. Into these notches rest the lower ends of the arms 23. The arms 23 are provided with T'shaped projections 32 which retain the arms above the plate 26. Press fit into holes in the lower ends or tips of the arms 23 are flanged nylon insulator inserts 34 through which extend pins 35. Attached to the pins 35 are springs 36 which are connected in tension between the pins 35 and a point on the lugs29, the point being displaced some distance radially inward from the pins 35. in this manner, the springs 36 serve to urge the lower ends of the arms '23 downwardly against the plate 26 and inwardly to retain the arms 23 in the notches 31 with the cooperation of the projections 32 on the arm 23. Furthermore,

by the arrangement of the spring 36, a moment is applied to the lower end of the arm 23 to cause the arm 23 to pivot such that the upper end 24 of the arm 23 is biasedoutwardly away from the central axis 22. A hollow tube 52 is mounted to the plate 26 and surrounds the central axis 22. At the upper end of the steel tube 52 is secured a brass or other non-ferrous material disc or plate 41 having ten symmetrically spaced radial slots 38 extending from the circumference thereof. Each of the arms 23 extends through a different one of the slots 38. A spacer ring 39 surrounds the arms 23 and is secured to the disc 41 to constrain the arms 23 against outward movement and, in cooperation with the disc 41, to retain the arms 23 parallel with the central axis and with each other when in their normal positions.

The disc 41 and spacer 39 are formed of insulator materiaLThe springs 36, as are the pins 35, are made of a silver plated beryllium copper which provides good spring elasticity and good electrical conductivity for a purpose which will be understood in connection with the discussiontof the electrical circuitry below.

The arms 23, when urged against the action of the spring 36, will pivot radially inward of the device 11 to a position where the arm 23 registers against the inner limits of the slots 38 in the insulator plate 41. Held in this position, the upper free end 24 of the arm 23 intersects the viewing axis 22 of the device 11, and is in an orientation such that this upper end 24 is perpendicular to the viewing axis 22. This is shown by the phantom lines in FIG. 2. The novel means for moving these arms to this inner position is described in more detail below.

As illustrated in FIG. 3, each of the free ends 24 bears upon it a different decimal digit, which, when the respective arm 23 carrying that digit is selectively positioned at the viewing axis 22, will present that respective selective digit for viewing at the central axis 22. This digit may be viewed in several ways. In one simple embodiment, the digit may be directly viewable by an observer through a window or opening in the housing which is positioned concentric with the central axis 22. In the preferred embodiment shown, however, this digit 44 is carried in the form of a transparent insert in the free end 24 of each of the arms 23, and means are further provided to project light through this transparent insert to illuminate the character and to thereafter project this illuminated characterimage onto a viewing screen. The means provided include an electric light bulb 51 positioned at the viewing axis and mounted in a mounting socket'45 which is carried by the plate 26, and in electrical contact therewith. The light is'surrounded by the'cylindrical tube 52 which is aligned concentric with the axis 22 and which extends from the base of the bulb 51 to a point immediately below the inner position of the free ends 24 of the arms 23. At this upper end 54 of the tube 52 a set of collimating lenses 55 is provided to project collimated light outwardly from the tube along the axis 22 and through the transparent digit insert 44 of the arm end 24. An objective lens 61 is provided in a lens mount 62 to which it is secured by a retaining spring 63 and which is rigidly secured to an axial plate 65 which may be secured in any manner, as, for example, to the wall of the housing 21. The lens is positioned so as to focus an image of the illuminated digit onto a frosted screen 68 which is secured to a cap 69 which is secured over the end of the housing 21.

The electrical circuitry of the device 11 includes a cluster of ten wires 81, each soldered to a different one of the brass lugs 29. The conductive springs 36, as connected, will electrically connect the lugs to the conductive pins 35. Soldered to each of the pins 35 is the lower lead of a winding or coil 92. The coil is of enameled copper wire and is wound about the arm 23. The upper lead of each of the coils 92 is soldered to the steel arms 23 which are electroplated with copper, nickel and gold to carry electric current and transmit magnetic flux therethrough. Similarly, the steel plate 26 and steel tube 52 are plated, and being in contact, form a common flux core and conductorwith each other. A winding 91, also of enameled copper wire, is wound about the tube 52 in such direction that common current passing through a coil 92 and the coil 91 will magnetize the arm 23 about which that coil 92 is wound and the tube 52 in opposite directions. The lower lead 82 of the coil 91 is brought directly from the housing 21 for external connection.

The lamp circuit includes lead 83 connected to a spring contact 84 mounted to plate 28 by an insulator 85.

Since each of the arms in its rest position is at a substantial distance from the center, the current required to start the am moving quickly is quite high. As the arm approaches the center coil the current required to move it becomes smaller and smaller until, when the two are in contact, the current required to hold them together is at a minimum. If the same current required to initiate arm movement were maintained for more than a few milliseconds the small number of turns in the arm coil would be burned up. In order to satisfy these electrical requirements the circuit shown in FIG. 5 was developed and found to work quite satisfactorily. The values shown are for the operation of one device 11 only, but modification of the circuitry common to more than one device when such are operated will be readily apparent to one skilled in the art.

Referring to FIG. 5, the electrical circuitry of the device of FIG. 2 is illustrated. This circuitry includes a DC power source 101 having a positive terminal 102 and a negative terminal 103. Connected in series across the source 101 is a variable resistor 104 and a capacitor 105. The juncture 106 of the capacitor resistor circuit is connected to the lower lead 82 of the central winding 91. The upper lead is connected to the upper end of the tube 52, which is plated with an electrically conductive material. The tube52 is electrically connected by a conductor 107 to each of the arms-23. This conductor 107 is in fact the supporting plate 26 in the embodiment illustrated. Each of the arms 23 is also plated with an electrically conductive material to serve as an electrical conductor to which is connected the upper lead of the winding 92. The lower lead of the winding 92 is connected through a switching device 121 to a bus line 122 which is connected to the negative terminal 103 of the power source 101. The switching devices 121 may be any type device which is effective to make or break a circuit. They may be mechanical switches or, as they would most likely be when the display device is used in connection with an electronic computer or calculator, may be solid state switching devices. Typically, these switching devices 121 would be included in the unit to which the display register 10 would be associated. They would in turn be operated by some selector 124 of the device which uses the display register.

Connected between the positive terminal 102 of the power source 101 and the conductor 107 (plate 26) is the display illuminating circuit which includes the light bulb 51 connected in series with a variable resistor 131. The values of the components which are shown in the drawing of FIG. 5 have been found to be suitable for the operation of a display device 11.

When the DC source 101 of from to volts is applied across the series connection of capacitor 105 and resistor 104 with the values shown, capacitor 105 charges up to voltage of the source 101 through resistor 104. If it is desired to display a numeral, it is only necessary to close a switch 121. Closing switch 121 places an arm coil 92 and the center coil 91 in series across capacitor 105. Since the series resistance of the two coils is only about 11 ohms and the capacitor is 200 microfarads, the time of discharge requires only about 20 milliseconds. This is the high intensity pulse which starts the arm 23 moving in toward the center axis 22. After the capacitor 105 has discharged, the holding current through 92 is equal to the voltage of source 101 divided by the resistance of coil 92 plus the equivalent resistance of coil 91 resistors 104 and 131 and bulb 51. In actual practice, this results in a starting voltage pulse of about 20 volts and ends with a holding voltage of about 1.5 volts across the two coils, and about 5 volts across the miniature light bulb 51. This very low holding voltage is adequate to maintain the arm in the projection position indefinitely. It should also be noticed that this circuit turns on the projection light bulb only at the time when the projected image is in place and the screen remains dark at all other times. Another feature of the circuit is that no current is drawn from the power supply unless a numeral is displayed. The foregoing combination of electrical actions is easily able to follow switching rates as high as 10 per second and cause the display device to follow faithfully.

In operation, selection of a particular one of the characters is effected by connecting the lower end of the central winding with the lower end of the lever winding bearing a selected character. Connection of the winding in this manner provides a flow of current through the central winding and the selected winding and, by reason of the windings being oppositely wound, polarizes the upper free end of the selected character lever oppositely of the upper end of the central tube. This opposite polarization causes the lever to be attracted toward the central axis.

The operation of the device is such that, when a selected one of the switches 121 is closed, current flows through the winding 91 and also through the winding 92 of the selected arm 23 to magnetize the tube 52 and the selected arm 23 in such a manner that a magnetic attractive force will be exerted between the upper end of the tube 52 and the upper end of the arm 23, which will draw the arm to the central position against the force of the spring 36. While a certain amount of attractive force would exist between the tube 52 and the other arms 23 which are not magnetized, due to the ferromagnetic nature of the arms, this force has been found to be insufficient to overcome the force of the spring 36. Additionally, due to the shape and symmetry of the free ends 24 of the arms 23, and since these forces will be exerted equally upon the non-selected arms, any exaggerated movement toward the center would be experienced equally by each of the arms and their ends would come into abutment with each other to prevent any of them from being moved toward the central axis (FIG. 3). Since a much stronger force would be exerted on the selector arm, this arm would move to the center before the abutting effect of the others would constrain it.

While only a single preferred embodiment of the invention is described, it will be readily apparent to those skilled in the art that many alternatives and modifications can be made in accordance with principles of the present invention, as embraced by the following claims:

I claim:

I. A device for selectively displaying indicia along a viewing axis, said device comprising:

a common ferromagnetic element located along said viewing axis,

a plurality of levers;

each of said levers having an indicia bearing free end;

said levers being pivotally mounted with their free ends movable into and out of a viewing position on said viewing axis;

said levers being biased outwardly from said viewing axis; and

selective moving means comprising means for selectively polarizing said levers into attraction with said ferromagnetic element along said viewing axis to move said indicia bearing free ends selectively into said viewing position.

2. A device according to claim 1 further comprising:

a light source positioned on said viewing axis; and

said indicia bearing free ends of said lever being transparent, whereby said indicia is viewable when said free end is positioned along said axis between said light source and an observer.

3. A device according to claim 2 further comprising:

a screen positioned along said viewing axis opposite said light source from said viewing position; and

a lens positioned on said viewing axis between said light source and said screen to project an image of said indicia upon said screen.

4. A device according to claim 1 wherein said indicia are numeric characters.

5. A device according to claim 4 wherein said indicia are decimal digits and said levers are ten in number, each bearing a different decimal digit.

6. Adevice according to claim 1 further comprising a ferromagnetic tube surrounding a light source on said viewing axis; and

a plurality of wire windings, one surrounding each of said levers and said tube;

a source of electrical potential; and

means for connecting the winding of said tube and the winding of a selected one of the levers across said source so as to magnetically polarize said tube and said selected lever oppositely whereby said selected lever is magnetically attracted toward said viewing axis with its indicia bearing free end in said viewing position.

7. A device according to claim 6 further comprising:

a selector for selectively connecting the winding of one of said levers in series with the winding of said tube.

8. A device according to claim 7 wherein:

said common element and said levers are electrically conductive;

one end of said common element winding is con- 'nected to said common element; one end of each of said lever windings is connected to said lever; and each of said levers is electrically connected to said common element. 9. A device according to claim 7 wherein: said lever windings are electrically connected in parallel with each other and in series with said common element winding.

10. A device according to claim 9 further comprising:

an electrical circuit path plated on said levers and said common element.

11. The indicia display device of claim 1 in which said levers are arranged in a circular array about said viewing axis.

12. The indicia display device of claim 1 in which said levers are at least partially made from ferromagnetic material and in which said selective moving means comprises a winding surrounding said common ferromagnetic element;

a plurality of windings, one surrounding each of said 'levers; i a source of electrical current; means for selectively connecting a selected one of said levers in series with said winding of said magnetically sensitive element and said source to cause current to pass therethrough; whereby the connecting of said windings to cause current to pass therethrough causes a free end of said selected lever to be magnetically deflected from said rest position to said energized position.

13. A device according to claim 8 further comprising:

a selector for selectively connecting the winding of one of said arms in series with the winding of said source so as to magnetically polarize said tube and said selected lever oppositely whereby said selected lever is magnetically attracted toward said viewing axis with its indicia bearing free end in said viewing position.

15. A display register for selectively displaying groups of indicia, said register comprising:

a plurality of display modules, each for selectively displaying a single indicia along a different viewing axis, each of said modules including:

a. a ferromagnetic element located along one of said viewing axes,

b. a plurality of levers,

c. each of said levers having an indicia bearing free end,

(I. said levers being pivotally mounted about said viewing axis with their free ends movable into and out of a viewing position on said viewing axis, and

e. selective moving means comprising means for selectively polarizing said levers into attraction with said element along said viewing axis to move said indicia bearing free ends selectively into said viewing position.

16. A device according to claim 15 wherein said levers of each of said modules are arranged in a circle about said viewing axis and are radially movable into and out of said position in said viewing axis.

17. A display register for selectively displaying groups of indicia, said register comprising:

a plurality of display modules, each for selectively displaying a single indicia along a different viewing axis, each of said modules comprising:

a. a light source for directing light along said viewing axis;

b. a ferromagnetic tubular element located on said viewing axis;

c. a plurality of levers surrounding said tubular element;

d. each of said levers having an indicia bearing free end;

e. the free ends of said levers being selectively movable into the path of said light source;

f. a collimating lens positioned between said light source and the free ends of said levers;

g. an objective lens positioned in said light path beyond the free ends of said levers;

h. a viewing screen located at the focal plane of said objective lens; and

i. selective moving means comprising means for selectively polarizing said levers into attraction with said ferromagnetic tubular element along said viewing axis to move said indicia bearing free ends selectively into said viewing position. 

1. A device for selectively displaying indicia along a viewing axis, said device comprising: a common ferromagnetic element located along said viewing axis, a plurality of levers; each of said levers having an indicia bearing free end; said levers being pivotally mounted with their free ends movable into and out of a viewing position on said viewing axis; said levers being biased outwardly from said viewing axis; and selective moving means comprising means for selectively polarizing said levers into attraction with said ferromagnetic element along said viewing axis to move said indicia bearing free ends selectively into said viewing position.
 2. A device according tO claim 1 further comprising: a light source positioned on said viewing axis; and said indicia bearing free ends of said lever being transparent, whereby said indicia is viewable when said free end is positioned along said axis between said light source and an observer.
 3. A device according to claim 2 further comprising: a screen positioned along said viewing axis opposite said light source from said viewing position; and a lens positioned on said viewing axis between said light source and said screen to project an image of said indicia upon said screen.
 4. A device according to claim 1 wherein said indicia are numeric characters.
 5. A device according to claim 4 wherein said indicia are decimal digits and said levers are ten in number, each bearing a different decimal digit.
 6. A device according to claim 1 further comprising a ferromagnetic tube surrounding a light source on said viewing axis; and a plurality of wire windings, one surrounding each of said levers and said tube; a source of electrical potential; and means for connecting the winding of said tube and the winding of a selected one of the levers across said source so as to magnetically polarize said tube and said selected lever oppositely whereby said selected lever is magnetically attracted toward said viewing axis with its indicia bearing free end in said viewing position.
 7. A device according to claim 6 further comprising: a selector for selectively connecting the winding of one of said levers in series with the winding of said tube.
 8. A device according to claim 7 wherein: said common element and said levers are electrically conductive; one end of said common element winding is connected to said common element; one end of each of said lever windings is connected to said lever; and each of said levers is electrically connected to said common element.
 9. A device according to claim 7 wherein: said lever windings are electrically connected in parallel with each other and in series with said common element winding.
 10. A device according to claim 9 further comprising: an electrical circuit path plated on said levers and said common element.
 11. The indicia display device of claim 1 in which said levers are arranged in a circular array about said viewing axis.
 12. The indicia display device of claim 1 in which said levers are at least partially made from ferromagnetic material and in which said selective moving means comprises a winding surrounding said common ferromagnetic element; a plurality of windings, one surrounding each of said levers; a source of electrical current; means for selectively connecting a selected one of said levers in series with said winding of said magnetically sensitive element and said source to cause current to pass therethrough; whereby the connecting of said windings to cause current to pass therethrough causes a free end of said selected lever to be magnetically deflected from said rest position to said energized position.
 13. A device according to claim 8 further comprising: a selector for selectively connecting the winding of one of said arms in series with the winding of said tube.
 14. A device according to claim 13 in which each of said ferromagnetic elements of each of said modules comprises a ferromagnetic tube surrounding a light source on said axis and said selected moving means comprises a plurality of wire windings, one surrounding each of said levers and said tube; a source of electrical potential; means for connecting winding of said tube and the winding of a selected one of said levers across said source so as to magnetically polarize said tube and said selected lever oppositely whereby said selected lever is magnetically attracted toward said viewing axis with its indicia bearing free end in said viewing position.
 15. A display register for selectively displaying groups of indicia, said register comprising: a plurality of display modules, each for selectively displaying a single indicia along a different viewing axis, each of said modules including: a. a ferromagnetic element located along one of said viewing axes, b. a plurality of levers, c. each of said levers having an indicia bearing free end, d. said levers being pivotally mounted about said viewing axis with their free ends movable into and out of a viewing position on said viewing axis, and e. selective moving means comprising means for selectively polarizing said levers into attraction with said element along said viewing axis to move said indicia bearing free ends selectively into said viewing position.
 16. A device according to claim 15 wherein said levers of each of said modules are arranged in a circle about said viewing axis and are radially movable into and out of said position in said viewing axis.
 17. A display register for selectively displaying groups of indicia, said register comprising: a plurality of display modules, each for selectively displaying a single indicia along a different viewing axis, each of said modules comprising: a. a light source for directing light along said viewing axis; b. a ferromagnetic tubular element located on said viewing axis; c. a plurality of levers surrounding said tubular element; d. each of said levers having an indicia bearing free end; e. the free ends of said levers being selectively movable into the path of said light source; f. a collimating lens positioned between said light source and the free ends of said levers; g. an objective lens positioned in said light path beyond the free ends of said levers; h. a viewing screen located at the focal plane of said objective lens; and i. selective moving means comprising means for selectively polarizing said levers into attraction with said ferromagnetic tubular element along said viewing axis to move said indicia bearing free ends selectively into said viewing position. 